In order to create more attractive packaging for various materials, packaging manufacturers have created containers wherein segments of the container can move relative to other portions of the container, allowing images or other graphics on a rotatable segment to be moved relative to graphics on fixed portions, or relative to graphics on other rotatable segments. Simple presentations involve a single rotating segment, which can be mixed and matched against adjacent fixed portions of the outer layer. A more complex presentation involves a fixed portion and two or more rotating segments. Such a presentation can, for example, use a fixed portion to show the lower torso of a cartoon character, with two rotatable segments presenting the upper torso and head. As the number of rings is increased, the potential variations between the images or graphics also increases.
One principle problem in forming rotatable segments has been in retaining the segments on the container. Where the container or rotatable segment is formed by injection molding, raised flanges or other retention devices can be formed on one or the other components to prevent a rotating segment from becoming separated from the container. Examples of such retention devices can be seen, for example, in U.S. Pat. No. 5,884,421. In this patent, flanges or rims are formed to prevent a rotating ring from separating from the container. Also, lips are formed on the outer shell. These flanges have the disadvantage of requiring the fabrication of the retention devices on one member or the other.
Another form of creating a rotatable segment on the exterior of a container involves forming a raised flange by bonding a non-rotating portion of the outer layer to the inner layer. Such a formation can be seen in U.S. Pat. No. 5,884,421. This method has the disadvantage of requiring accurate placement of the bonding agent to keep it from binding rotating segments to the inner layer.
Another method of creating a twist container uses a simple cylindrical tube, often formed of cardboard or a similar inexpensive material. Concentric segments are placed around the outside of the tube, and retained about the tube by joining the topmost and bottom most segments to the inner cylinder. A bead may be used to join the top edges of the inner and outer layers. These containers are called beaded-top twist containers. One disadvantage of this method is that a substantial portion of the outer layer at both the top and bottom remains fixed to the inner layer. Since both the top and bottom are fixed, the graphics or images on the top and bottom portion of the outer layer are fixed relative to each other. This limits the variations which can be presented.
Beaded-top twist containers incorporating rotatable segments are generally cylindrical in shape in the area where a rotatable segment is assembled to the container. As a convention, the cylinder is described as being oriented such that the open ends of the cylinder face up and down, with the long center axis of the cylinder being vertical. A bottom closure is provided to seal the bottom opening of the cylinder, and typically consists of a thin metal plate, the edges of which are crimped around the bottom edge of the cylindrical tube. The top closure can be fabricated in a variety of manners, dependent on the intended use and allowable cost of the container. Typical methods are to form a bead around the edge of the cylindrical tube by outwardly rolling the edge, or to crimp a metallic element to the edge. A closure for the top of the container can then be formed by bonding a membrane to the bead. Alternately, or additionally, a plastic cap can be placed over the bead at the top edge of the container. Yet another alternate top closure incorporates a cap or metal end which is crimped or bonded to the top edge of the cylindrical container, similar to the bottom closure described above. The cap may be scored to allow removal of the center section of the cap using a pull tab.
Rotatable segments can also be formed from the outer layer by cutting the outer layer into segments after the outer layer has been assembled around the inner layer. The separation can be accomplished by a scoring operation, which involves cutting through the outer layer of the container without destroying the integrity of the inner layer. The integrity of the inner layer is destroyed when it is cut through by the scoring operation, or cut through sufficiently to significantly weaken the inner layer. The scoring can be accomplished by running a sharp edge along the path desired to form the separation line between segments. Pressure must be applied to the sharp edge to cause it to cut the outer layer. The scoring operation typically does not remove outer layer material, but rather severs adjacent portions of the material.
The total height of the segments after the outer layer has been segmented is not significantly reduced from the height of the outer layer before the outer layer is segmented. This can cause a mechanical interference between the segments of the outer layer, preventing them from turning relative to other segments or fixed portions of the outer layer. This interference can apply unwanted pressure to the beads incorporated in the top and bottom closures, potentially causing the beads to be damaged. The friction caused by the interference may reduce itself over time, however the initial perception of the twist container is not positive, as it may be difficult to rotate the segments.